Display device

ABSTRACT

A display device includes a reflective image display unit having a sheet-like anisotropic scattering member. The sheet-like anisotropic scattering member has a surface in which both a low refractive index area and a high refractive index area exist. The sheet-like anisotropic scattering member is disposed so that a light enters from a first surface thereof and exits as scattered light from a second surface thereof, when an extent of refractive index difference at a boundary or vicinity thereof between the low refractive index area and the high refractive index area is relatively large in the first surface and relatively small in the second surface.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/749,006, filed Jun. 24, 2015, which applicationis a continuation of U.S. patent application Ser. No. 14/155,872, filedJan. 15, 2014, and issued as U.S. Pat. No. 9,091,877 on Jul. 28, 2015,which application claims priority to Japanese Priority PatentApplication JP 2013-005817 filed in the Japan Patent Office on Jan. 16,2013, the entire content of which is hereby incorporated by reference.

BACKGROUND

1. Field of the Invention

The present disclosure relates to a display device, and morespecifically to a display device including an image display unitprovided with a sheet-like anisotropic scattering member.

2. Description of the Related Art

There is known a reflective image display unit that displays an image bycontrolling the reflection ratio of external light or incident light. Areflective liquid crystal display panel, for example, includes areflecting electrode that reflects incident light. The reflective liquidcrystal display panel displays an image by controlling the reflectionratio of incident light with a liquid crystal material layer. Since adisplay device including such a reflective image display unit usesincident light from outside to display an image, it is possible to savethe power consumption and reduce in its weight and thickness. Suchdisplay devices are used for portable electronic apparatuses, forexample.

In such a display device including a reflective image display unit, itis possible to increase the reflection ratio for a given observationpoint and thus compensate for the reduction of reflection ratio in colordisplaying, by imparting an angle dependency to the light scatteringproperty or characteristics in a display area of the image display unit.It is also possible to prevent an image from being seen or observed ator from a point other than a given observation point. For example,Japanese Patent Application Laid-open Nos. 2000-297110 and 2008-239757describe an anisotropic scattering member with a plurality of areashaving different refractive indexes which may be used for controlling aviewing angle of the display device.

In a display device employing such an anisotropic scattering member, anadverse iridescence such as rainbow-colored glare may occur because ofoptical interference due to a microstructure of the anisotropicscattering member. Thus, a display quality may be deteriorated.

Therefore, there is a need for a display device capable of reducingiridescence (ex. rainbow-colored glare) which may occur due to astructure of an anisotropic scattering member.

SUMMARY

It is an object of the present invention to at least partially solve theproblems in the conventional technology.

There is provided a display device including a reflective image displayunit having a sheet-like anisotropic scattering member, wherein thesheet-like anisotropic scattering member has a surface in which both alow refractive index area and a high refractive index area exist, thesheet-like anisotropic scattering member is disposed so that a lightenters from a first surface of the sheet-like anisotropic scatteringmember and exits as scattered light from a second surface of thesheet-like anisotropic scattering member, when an extent of refractiveindex difference at a boundary or vicinity thereof between the lowrefractive index area and the high refractive index area is relativelylarge in the first surface and relatively small in the second surface,and the display device satisfies mathematical formulae,

0.7<T(θ−φ)/T(θ)≦1

θ<0

wherein 2φ represents a scattering angle range, θ represents apredetermined main incident angle of light entering the scatteringmember, T(a) represents a transmittance at a position on an extensionline of an incident direction of the light with an incident angle “a”.

The above and other objects, features, advantages and technical andindustrial significance of this invention will be better understood byreading the following detailed description of presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic perspective view of a display device according toa first embodiment;

FIG. 2A is a schematic perspective view for explaining a configurationof a reflective image display unit;

FIG. 2B is a schematic sectional view for explaining a structure of ananisotropic scattering member according to the first embodiment;

FIG. 2C is a schematic perspective view for explaining arrangement of alow refractive index area and a high refractive index area in theanisotropic scattering member;

FIG. 2D is a schematic perspective view for explaining anotherarrangement of the low refractive index area and the high refractiveindex area in the anisotropic scattering member;

FIG. 3A is a schematic view for explaining a method for manufacturingthe anisotropic scattering member according to the first embodiment;

FIG. 3B is another schematic view for explaining the method formanufacturing the anisotropic scattering member according to the firstembodiment;

FIG. 4A is a schematic view for explaining a relation between incidentlight and scattered light in the anisotropic scattering member;

FIG. 4B is another schematic view for explaining the relation betweenincident light and scattered light in the anisotropic scattering member;

FIG. 5 is a schematic view for explaining a positional relation betweenthe display device and an image observer when substantially parallelexternal light enters;

FIG. 6A is a schematic sectional view of the reflective image displayunit according to the first embodiment;

FIG. 6B is a schematic sectional view of a reflective image display unitaccording to a comparative embodiment;

FIG. 7 is a schematic view for explaining a relation between incidentlight and scattered light in the anisotropic scattering member;

FIG. 8 is a schematic view illustrating results obtained by measuringperformance of the anisotropic scattering member;

FIG. 9A is a schematic view for explaining a relation between incidentlight and scattered light in the anisotropic scattering member;

FIG. 9B is another schematic view for explaining the relation betweenincident light and scattered light in the anisotropic scattering member;

FIG. 10A is a schematic view for explaining a relation between incidentlight and scattered light in the anisotropic scattering member;

FIG. 10B is another schematic view for explaining the relation betweenincident light and scattered light in the anisotropic scattering member;

FIG. 11 is still another schematic view for explaining the relationbetween incident light and scattered light in the anisotropic scatteringmember;

FIG. 12A is a schematic sectional view of a reflective image displayunit according to a second embodiment;

FIG. 12B is a schematic sectional view of a reflective image displayunit according to a comparative embodiment;

FIG. 13 is a schematic exploded perspective view of a reflective imagedisplay unit according to a third embodiment;

FIG. 14 is a schematic exploded perspective view of a reflective imagedisplay unit according to a fourth embodiment; and

FIG. 15 is a schematic sectional view of the reflective image displayunit according to the fourth embodiment.

DETAILED DESCRIPTION

The present disclosure will now be described according to the followingorders and with reference to the accompanying drawings. The followingdescription is only for illustrative purpose. Any change, rearrangement,modification or the like readily derived from or substantiallyequivalent with the present disclosure without departing from the spiritand scope of the invention is encompassed within the present invention.For better understanding of the disclosure, the accompanying drawingsmay be schematic and not to scale with actual width, thickness, shapesof individual elements or components in actual embodiments. In any case,the accompanying drawings are for illustrative purpose only and not tobe construed as any limitation of the present disclosure. In thefollowing description and drawings, the corresponding elements orcomponents in the plurality of drawings carry the identical numericreferences, and the redundant explanation may be omitted as appropriate.

1. General Configuration of Display Device

2. First Embodiment

3. Second Embodiment

4. Third Embodiment

5. Fourth Embodiment (and others)

[General Configuration of Display Device]

An anisotropic scattering member according to the present disclosuretransmits light entered from a predetermined direction and scatterslight entered from another predetermined direction. In a display deviceaccording to the present disclosure, the anisotropic scattering membermay be disposed so that the scattered light is emitted when a lightreflected in the image display unit passes through the anisotropicscattering member. Alternatively, the anisotropic scattering member maybe disposed so that the scattered light is emitted when an incidentlight from outside passes through the anisotropic scattering member.

The anisotropic scattering member can be formed with using a compositionor the like containing a photoreactive compound. For example, theanisotropic scattering member can be obtained in such a manner that abase material made of a composition whose refractive index changes to acertain extent before and after photopolymerization is irradiated with alight such as UV light from a predetermined direction. As ingredients orcomponents of the composition, appropriate materials whose refractiveindex changes to a certain extent between a photoreacted portion and theother portion can be selected from known photoreactive materials such aspolymer or the like having a radical polymerizable functional group or acation polymerizable functional group.

The anisotropic scattering member also can be obtained in such a mannerthat a base material made of a composition for which a photoreactivecompound and a non-photoreactive high molecular compound are mixed isirradiated with a light such as UV light from a predetermined direction.The non-photoreactive high molecular compound can be selected asappropriate from known materials such as acrylic resin, styrene resinand the like, for example.

The base material made of aforementioned compositions can be obtained insuch a manner that appropriate composition is applied on a polymer filmbase body by a known application method.

In a surface of the anisotropic scattering member made from theaforementioned composition, both a low refractive index area and a highrefractive index area exist. A boundary between the low refractive indexand the high refractive index forms a predetermined angle relative to athickness direction of the anisotropic scattering member. Depending onthe situation, it is possible to arrange the angle so that the anglecontinuously changes in the in-plane or surface direction.

Qualitatively, when the base material made of the composition isirradiated with light, closer the irradiation side, faster thephotoreaction of the composition. Therefore, a surface irradiated withlight is likely to be a surface where an extent of refractive indexdifference at a boundary or vicinity thereof between the low refractiveindex area and the high refractive index area is relatively large. Incontrast, an opposite surface is likely to be a surface where an extentof refractive index difference at a boundary or vicinity thereof betweenthe low refractive index area and the high refractive index area isrelatively small.

The refractive index difference between the low refractive index areaand the high refractive index area is preferably and usually not lessthan 0.01, more preferably not less than 0.05, and still more preferablynot less than 0.10, in a vicinity of a surface where the refractiveindex difference at a boundary or vicinity thereof between the lowrefractive index area and the high refractive index area is relativelylarge.

Depending on the materials and/or manufacturing method, the anisotropicscattering member can be formed so that the photoreacted portion and theother portion take various shapes. For example, the photoreacted portionand the other portion may take a louver-like shape or configuration. Thephotoreacted portion and the other portion may be formed as one or morecolumn-like portions and a surrounding portion thereof.

Examples of a reflective image display unit constituting the displaydevice according to the present disclosure include, but are not limitedto, a reflective liquid crystal display panel, etc. The image displayunit may perform monochrome display or color display. The reflectiveliquid crystal display panel includes reflecting electrodes that reflectexternal light, for example. The reflective liquid crystal display paneldisplays an image by controlling the reflection ratio of external lightwith a liquid crystal material layer.

The reflective liquid crystal display panel is formed of a frontsubstrate provided with transparent common electrodes, a back substrateprovided with pixel electrodes, and the liquid crystal material layerarranged between the front substrate and the back substrate, forexample. The pixel electrodes themselves may be provided as reflectingelectrodes and reflect light. Alternatively, a reflective film mayreflect light in a combination of transparent pixel electrodes and thereflective film. An operating mode of the liquid crystal display panelis not particularly restricted as long as the operating mode does notinterfere with a reflective display operation. The liquid crystaldisplay panel may be driven in what is called a vertical alignment (VA)mode or an electrically controlled birefringence (ECB) mode, forexample.

In the display device according to the present disclosure having thevarious types of preferable configurations described above, the imagedisplay unit may be formed of the reflective liquid crystal displaypanel. The reflective liquid crystal display panel includes the frontsubstrate, the back substrate, and the liquid crystal material layerarranged between the front substrate and the back substrate. Theanisotropic scattering member may be disposed on the front substrateside.

In the display device according to the present disclosure having thevarious types of preferable configurations described above, theanisotropic scattering member may be formed by laminating a plurality ofscattering members having different scattering characteristics.

Transflective image display units having both reflective andtransmissive characteristics are widely known, including a transflectiveliquid crystal display panel provided with both a reflective displayarea and a transmissive display area in a pixel, for example. In somecases, the image display unit may be such a transflective image displayunit. In other words, the “reflective image display unit” includes a“transflective image display unit”.

The shape of the image display unit is not particularly restricted andmay be a horizontally long rectangle or a vertically long rectangle.Assuming that (M,N) denotes the number of pixels M×N in the imagedisplay unit, a horizontally long rectangular image display unit mayhave some types of image display resolution, such as (640,480),(800,600), and (1024,768), as the value of (M,N), for example. Bycontrast, a vertically long rectangular image display unit may haveresolution obtained by switching the values described above, forexample. The resolution is not limited to these values.

A drive circuit that drives the image display unit may be formed ofvarious circuits. These circuits may be formed using well-known circuitelements, for example.

Various types of conditions described in the present specification aresatisfied in a substantial manner besides in a strict manner. Variousfluctuations in design and manufacture are allowable.

First Embodiment

A first embodiment relates to a display device according to the presentdisclosure. FIG. 1 is a schematic perspective view of the display deviceaccording to the first embodiment.

As illustrated in FIG. 1, a display device 100 includes a reflectiveimage display unit 1 having a display area 11 in which pixels 12 arearrayed. The image display unit 1 is formed of a reflective liquidcrystal display panel and is incorporated in a housing 40. The imagedisplay unit 1 is driven by a drive circuit, which is not illustrated,for example. In FIG. 1, a part of the housing 40 is cut out. Externallight, such as sunlight, enters the display area 11. For convenience ofexplanation, an assumption is made that the display area 11 is parallelto the X-Y plane and that the side from which an image is observed ispositioned in the +Z-direction.

FIG. 2A is a schematic perspective view for explaining the configurationof the reflective image display unit. FIG. 2B is a schematic sectionalview for explaining a structure of an anisotropic scattering memberaccording to the first embodiment. FIG. 2C and FIG. 2D are schematicperspective views for explaining arrangement of a low refractive indexarea and a high refractive index area in the anisotropic scatteringmember.

The image display unit 1 illustrated in FIG. 2A is a reflective imagedisplay unit including a sheet-like anisotropic scattering member 20.More specifically, the image display unit 1 is formed of a reflectiveliquid crystal display panel including a front substrate, a backsubstrate, and a liquid crystal material layer arranged between thefront substrate and the back substrate. The image display unit 1 isformed by laminating a laminated body 10, the anisotropic scatteringmember 20, and a laminated body 30. The laminated body 10 illustrated inFIG. 2A serves as a part of the liquid crystal display panel. Thelaminated body 10 is formed by laminating a front substrate 18, a backsubstrate 14, and a liquid crystal material layer 17 arranged betweenthe front substrate 18 and the back substrate 14 illustrated in FIG. 6A,which will be described later. The anisotropic scattering member 20serves as a part of the liquid crystal display panel and is disposed onthe front substrate 18 side. The laminated body 30 illustrated in FIG.2A is formed by laminating a quarter-wave plate 31, a half-wave plate32, and a polarizing plate 33 illustrated in FIG. 6A.

As illustrated in FIG. 2A, the image display unit 1 has a rectangularshape. The sides of the image display unit 1 are denoted by referencenumerals of 13A, 13B, 13C and 13D. The side 13C is a side on the frontside, and the side 13A is a side opposite to the side 13C. The sides 13Aand 13C have a length of approximately 12 cm, whereas the sides 13B and13D have a length of approximately 16 cm, for example. These lengths aregiven as examples only.

The anisotropic scattering member 20 is a sheet (a film) having athickness of approximately 0.02 to 0.5 mm, for example. As illustratedin FIG. 2B, the surface of the anisotropic scattering member 20 isformed as a region in which a low refractive index area 21 and a highrefractive index area 22 are mixed in a micron order. For convenience ofillustration, FIG. 2A to FIG. 2D and other figures do not illustrate atransparent film serving as a base sheet of the anisotropic scatteringmember 20, for example.

The anisotropic scattering member 20, which will be described later indetail with reference to FIG. 6A, is disposed so that an external lightenters from a first surface and the incident light scatters from asecond surface. The first surface is a side where an extent of change ofthe refractive index is relatively large near a boundary between the lowrefractive index area 21 and the high refractive index area 22. Thesecond surface is a side where an extent of change of the refractiveindex is relatively small near a boundary between the low refractiveindex area 21 and the high refractive index area 22. In the firstembodiment, the anisotropic scattering member 20 is disposed so that theexternal light reflected inside of the image display unit 1 scatterswhen passing through the anisotropic scattering member 20.

The anisotropic scattering member 20 is formed of a composition or thelike containing a photoreactive compound, for example. As illustrated inFIG. 2C, the anisotropic scattering member 20 may have a structure inwhich the low refractive index area 21 and the high refractive indexarea 22 are formed in a louver-like manner, for example. Alternatively,as illustrated in FIG. 2D, the anisotropic scattering member 20 may havea structure in which the high refractive index area 22 and the lowrefractive index area 21 form column-shaped areas and a peripheral areasurrounding the column-shaped areas, respectively. In an exampleillustrated in FIG. 2D, a composition part which has been photoreactedtransforms into the high refractive index area in a column-shapedmanner.

Although the widths of the low refractive index areas 21 in thethickness direction and the widths of the high refractive index areas 22in the thickness direction are depicted as constant in FIG. 2C, this isgiven as an example only. Similarly, although the shapes of thecolumn-shaped areas are depicted as the same in FIG. 2D, this is givenas an example only.

In the anisotropic scattering member 20, the low refractive index area21 and the high refractive index area 22 are formed in an obliquedirection such that the boundary between the low refractive index area21 and the high refractive index area 22 forms an angle α with respectto the thickness direction (Z-direction) of the anisotropic scatteringmember 20 as illustrated in FIG. 2B to FIG. 2D. The angle α is set to apreferable value as appropriate depending on specifications of theanisotropic scattering member 20, for example. In some cases, the angleα may be set to 0 degree.

As illustrated in FIG. 4A and FIG. 4B, which will be described later, ascattering central axis S of the anisotropic scattering member 20 isinclined with respect to the normal direction (Z-axis direction) of theobservation surface of the display device 100. The scattering centralaxis S is an axis around which an anisotropic scattering characteristicsof the incident light becomes substantially symmetrical. In other words,the scattering central axis S is an axis extending in an incidentdirection of the most scattering light. The scattering central axis S isinclined basically in the same direction as the extending direction ofthe low refractive index area 21 and the high refractive index area 22.The inclination angle of the scattering central axis S may be the sameas or different from the inclination angle of the extending direction ofthe low refractive index area 21 and the high refractive index area 22.In the case illustrated in FIG. 2C, the azimuth in which the scatteringcentral axis S is projected on the X-Y plane corresponds to a directionperpendicular to the direction in which the louver-like areas extend. Inthe case illustrated in FIG. 2D, the azimuth corresponds to a directionin which a shadow obtained by projecting the column-shaped area on theX-Y plane extends.

For convenience of explanation, an assumption is made that the lowrefractive index area 21 and the high refractive index area 22 are eachformed in a louver-like manner and that the direction in which thelouver-like areas extend is parallel to the X-direction as illustratedin FIG. 2C. While the high refractive index area 22 is described as anarea in which a base material causes photoreaction, this is given as anexample only. The area in which the base material causes photoreactionmay be the low refractive index area 21.

The following describes a method for manufacturing the anisotropicscattering member 20 with reference to FIG. 3A and FIG. 3B. FIG. 3A andFIG. 3B are schematic views for explaining a method for manufacturingthe anisotropic scattering member according to the first embodiment. Asillustrated in FIG. 3A, the anisotropic scattering member 20 can bemanufactured by: coating a base substance, such as a polyethyleneterephthalate (PET) film, with a photoreactive composition to obtain abase material 20; and irradiating the base material 20′ with lightobliquely from a light irradiation device 50 through a mask 60 havingopenings 61, for example. In some cases, the base material 20′ may beirradiated with light without using the mask 60. The surface of the basematerial 20′ irradiated with the light output from the light irradiationdevice 50 is referred to as A-surface, whereas the side opposite theretois referred to as a B-surface.

Influences of diffraction of light, light absorption caused by thecomposition, and other factors qualitatively facilitate photoreaction inthe composition at a portion closer to the light irradiation side. As aresult, the A-surface irradiated with the light is a surface in which achange in the refractive index occurring near the boundary between thelow refractive index area 21 and the high refractive index area 22 isrelatively large as illustrated in FIG. 3B. By contrast, the B-surfaceopposite thereto is a surface in which a change in the refractive indexoccurring near the boundary between the low refractive index area 21 andthe high refractive index area 22 is relatively small.

By adjusting the angle of the irradiation light, it is possible to setthe angle α of the boundary between the low refractive index area 21 andthe high refractive index area 22 with respect to the thicknessdirection (Z-direction) of the anisotropic scattering member 20 tovarious angles in the anisotropic scattering member 20. By adjusting theinterval between the irradiation positions of the irradiation pattern,it is possible to adjust the interval between the boundaries of the lowrefractive index area 21 and the high refractive index area 22 and theinterval between the high refractive index area 22 and the highrefractive index area 22, for example.

The following describes the difference between the case where externallight enters the A-surface of the anisotropic scattering member 20 andthe case where external light enters the B-surface with reference toFIG. 4A and FIG. 4B. FIG. 4A and FIG. 4B are schematic views forexplaining a relation between incident light and scattered light in theanisotropic scattering member. FIG. 4A and FIG. 4B are different fromeach other in the light incident directions.

As illustrated in FIG. 4A and FIG. 4B, if light enters the anisotropicscattering member 20 in a direction substantially along the direction inwhich the boundary between the low refractive index area 21 and the highrefractive index area 22 extends, the light is scattered and then exitsfrom the anisotropic scattering member 20. By contrast, if light entersthe anisotropic scattering member 20 in a direction substantiallyperpendicular to the direction in which the boundary between the lowrefractive index area 21 and the high refractive index area 22 extends,the light passes through the anisotropic scattering member 20 withoutany change.

If light enters the B-surface and exits as scattered light from theA-surface as illustrated in FIG. 4A, the scattered light exits from thesurface where an extent of refractive index difference at a boundary orvicinity thereof between the low refractive index area 21 and the highrefractive index area 22 is relatively large. Therefore, opticalinterference due to a microstructure makes the iridescence(rainbow-colored glare) noticeable.

In contrast, if light enters the A-surface and exits as scattered lightfrom the B-surface as illustrated in FIG. 4B, the scattered light exitsfrom the surface where an extent of refractive index difference at aboundary or vicinity thereof between the low refractive index area 21and the high refractive index area 22 is relatively small. Therefore, itis possible to reduce the iridescence (rainbow-colored glare) caused byoptical interference due to a microstructure.

FIG. 5 is a schematic view for explaining a positional relation betweenthe display device and an image observer when substantially parallelexternal light enters. In FIG. 5, an image observer observes an image ata position distant from the display area 11 by a distance LZ in thestate where the incident direction of the external light and the normaldirection of the image display unit 1 form an angle β. YD denotes thelength of the surface inclined with respect to the incident direction ofthe external light by the angle β in the image display unit 1.

The following describes behavior of light in the image display unit 1when display is being performed in the positional relation illustratedin FIG. 5 with reference to FIG. 6A and FIG. 6B. FIG. 6A is a schematicsectional view of the reflective image display unit according to thefirst embodiment. FIG. 6B is a schematic sectional view of a reflectiveimage display unit according to a comparative embodiment.

In the image display unit 1 illustrated in FIG. 6A, a planarizing film15 made of a polymeric material, such as acrylic resin, is formed on theback substrate 14 made of a glass material, for example. Reflectingelectrodes (pixel electrodes) 16 made of a metallic material, such asaluminum, are formed on the planarizing film 15. The reflectingelectrodes 16 each have a mirror-like surface and are provided torespective pixels 12. To control electrical connection between signallines and the reflecting electrodes 16, elements including thin filmtransistors (TFT) are coupled to the respective pixels 12. FIG. 3A doesnot illustrate various wirings including the TFTs and the signal lines.

In the image display unit 1 illustrated in FIG. 6A, the front substrate18 made of a glass material is provided with common electrodes, whichare not illustrated, made of a transparent conductive material, such asindium tin oxide (ITO), for example. To perform color display, the pixel12 is formed of a group of sub-pixels, and color filters and othercomponents are provided to the respective sub-pixels. For convenience ofillustration, FIG. 6A does not illustrate the common electrodes, forexample.

The liquid crystal material layer 17 is arranged between the frontsubstrate 18 and the back substrate 14. In the liquid crystal materiallayer 17, liquid crystal molecules 17A are oriented in a predetermineddirection. The liquid crystal material layer 17 has a thickness largeenough to act as a half-wave plate when light is reciprocated by aspacer, which is not illustrated, in predetermined conditions, forexample.

The anisotropic scattering member 20 is disposed on the side opposite tothe liquid crystal material layer 17 side of the front substrate 18. Thequarter-wave plate 31, the half-wave plate 32, and the polarizing plate33 are arranged above the anisotropic scattering member 20.

An incident light entered from outside is formed into a linear polarizedlight with a predetermined direction through the polarizing plate 33.After that, the linear polarized light is formed into a circularpolarized light through the half-wave plate 32 and the quarter-waveplate 31. A combination of the half-wave plate 32 and the quarter-waveplate 31 functions as a broadband quarter-wave plate. The circularpolarized light enters the scattering member 20 from a directionorthogonal or almost orthogonal to a direction in which a boundarybetween the low refractive index area 21 and the high refractive indexarea 22 extends. Therefore, the circular polarized light passes throughthe scattering member 20 without scattering, then passes through theliquid crystal material layer 17, and reaches the reflecting electrode16. The light is reflected on the reflecting electrode 16 and passesthrough the liquid crystal material layer 17. Thus, the light entersfrom A-surface and exits from B-surface of the anisotropic scatteringmember 20. Since the light enters the scattering member 20 from adirection along or substantially along a direction in which a boundarybetween the low refractive index area 21 and the high refractive indexarea 22 extends, the light exits as scattered light from the scatteringmember 20. However, since the scattered light exits from a surface wherean extent of refractive index difference at a boundary or vicinitythereof between the low refractive index area 21 and the high refractiveindex area 22 is relatively small, the iridescence caused by opticalinterference due to a microstructure is reduced. Then, the scatteredlight reaches the polarizing plate 33 through the quarter-wave plate 31and the half-wave plate 32. From the polarizing plate 33, the lightemits toward outside. It is possible to control an amount of the lightwhich is reflected by the reflecting electrode 16 and passing throughthe polarizing plate 33, by controlling an electric voltage applied tothe reflecting electrode 16 or the like and thus controlling thealignment state of the liquid crystal molecular 17A in the liquidcrystal material layer 17.

By contrast, the following describes behavior of light in the case wherethe A-surface and the B-surface are upside down in the anisotropicscattering member 20. Now, with reference to FIG. 6B, an explanationwill be made on behavior of light in an image display unit 1′ accordingto a comparative embodiment in which the A-surface and the B-surface areupside down in the anisotropic scattering member 20.

In this case, behavior performed until external light reflected by thereflecting electrode 16 passes through the liquid crystal material layer17 is the same as the behavior described above. The reflected lightpasses through the liquid crystal material layer 17. The reflected lightthen enters the B-surface of the anisotropic scattering member 20 andexits from the A-surface. Because the light enters from a directionalong or substantially along a direction in which the boundary betweenthe low refractive index area 21 and the high refractive index area 22extends, the light is scattered. The scattered light exits from thesurface where an extent of refractive index difference at a boundary orvicinity thereof between the low refractive index area 21 and the highrefractive index area 22 is relatively large. Therefore, opticalinterference due to a microstructure makes the iridescence (ex.rainbow-colored glare) noticeable.

Thus, in the first embodiment, the anisotropic scattering member isdisposed so that a light enters from A-surface and exits as scatteredlight from B-surface, when an extent of refractive index difference at aboundary or vicinity thereof between the low refractive index area andthe high refractive index area is relatively large in A-surface andrelatively small in B-surface. More specifically, the anisotropicscattering member is disposed so that a light is scattered when thelight reflected in the image display unit passes through the anisotropicscattering member toward outside. Since the light is scattered whenexiting from the surface where an extent of refractive index differenceat a boundary or vicinity thereof between the low refractive index areaand the high refractive index area is relatively small, the iridescence(ex. rainbow-colored glare) caused by optical interference due to amicrostructure can be reduced.

Assuming that 2φ denotes a scattering angular range, θ denotes a mainincident angle of set light, and T(a) denotes transmittance at aposition on an extension line in the incident direction of the light atan incident angle a, the main incident angle θ satisfies θ<0, and theanisotropic scattering member 20 satisfies 0.7<T(θ−φ)/T(θ)≦1.

The relation described above will be explained with reference to FIG. 7to FIG. 11. FIG. 7 is a schematic view for explaining a relation betweenincident light and scattered light in the anisotropic scattering member.FIG. 8 is a schematic view illustrating results obtained by measuringperformance of the anisotropic scattering member. FIG. 9A is a schematicview for explaining a relation between incident light and scatteredlight in the anisotropic scattering member. FIG. 9B is another schematicview for explaining the relation between incident light and scatteredlight in the anisotropic scattering member. FIG. 10A is a schematic viewfor explaining a relation between incident light and scattered light inthe anisotropic scattering member. FIG. 10B is another schematic viewfor explaining the relation between incident light and scattered lightin the anisotropic scattering member. FIG. 11 is still another schematicview for explaining the relation between incident light and scatteredlight in the anisotropic scattering member.

The following describes the main incident angle of set light θ and thescattering angular range 2φ according to the present embodiment. Themain incident angle θ is an angle at which external light La is set tobe incident in designing. The main incident angle θ is 0 when theexternal light La enters perpendicularly (vertically) to the surface ofthe anisotropic scattering member 20. A direction in which the mainincident angle θ rotates closer to the image observer from the verticaldirection corresponds to a positive direction, whereas a direction inwhich the main incident angle θ rotates away from the image observerfrom the vertical direction corresponds to a negative direction. In FIG.7, the main incident angle θ has a negative value.

The scattering angular range 2φ is an angular range in which incidentlight can be scattered when the light enters the anisotropic scatteringmember 20 at various angles as the main incident angle θ. Specifically,when light enters at a central angle of an angular unit that scatterslight in the anisotropic scattering member 20, the anisotropicscattering member 20 outputs light spreading out at an angle φ in thepositive direction with respect to the incident angle and at an angle φin the negative direction. The scattering angular range 2φ is also anangular range in which transmittance is reduced. The transmittance ismeasured for each angle at a position on an extension line in theincident direction of the light when the light enters. The angular rangein which the transmittance is reduced corresponds to a range in whichthe incident light does not pass through the anisotropic scatteringmember 20 without any change. In other words, the angular range in whichthe transmittance is reduced is an angular range in which the incidentlight is scattered. Thus, the scattering angular range 2φ is an angularrange in which the incident light is scattered.

As illustrated in FIG. 7, the external light La incident at the mainincident angle θ of a negative angle passes through the anisotropicscattering member 20 and is reflected by the reflecting electrode 16.The external light La then passes through the anisotropic scatteringmember 20 again and is output from the display device 1. Light Lb isoutput at an angle −θ (an angle θ in the positive direction) among thelight that is reflected by the reflecting electrode 16, passes throughthe anisotropic scattering member 20 again, and is output from thedisplay device 1. The light Lb is light not being scattered among theexternal light La. Light Lc is output at an angle |θ|−φ among the lightthat is reflected by the reflecting electrode 16, passes through theanisotropic scattering member 20 again, and is output from the displaydevice 1. The light Lc is light rotated closer to the external light Laside than the light Lb by an angle φ. The light Lc corresponds to an endon the external light La side in the case where the external light Laincident at the main incident angle θ is scattered in the widest rangeby the anisotropic scattering member 20.

T(a) denotes the transmittance at a position on the extension line inthe incident direction of the light obtained when the light enters theanisotropic scattering member 20 at the incident angle a. Thedistribution of the transmittance in the anisotropic scattering member20 was measured. FIG. 8 illustrates the measurement result. In FIG. 8,the abscissa represents an angle (deg), and the ordinate representstransmittance (Y) (%) at a position rotated with respect to the incidentangle by 180 degrees. FIG. 8 also illustrates a measurement result oftransmittance distribution in another anisotropic scattering memberhaving different characteristics as a comparative example. Thetransmittance distribution with which iridescence is seen in FIG. 8 isthe distribution of the transmittance T(a) in the anisotropic scatteringmember 20 according to the present embodiment. The transmittancedistribution with which no iridescence is seen in FIG. 8 is thedistribution of the transmittance T(a) in the anisotropic scatteringmember according to the comparative example.

An examination is made of the case where the main incident angle θ isset to −20° and the scattering angular range 2φ is set to 50° in thetransmittance distribution illustrated in FIG. 8. A part of the lightincident as the external light La is reflected to be the light Lb of anangle of 20° (−θ), whereas another part thereof is reflected to be thelight Lc of an angle of −5° (|θ|−φ). In this case, the anisotropicscattering member 20 according to the present embodiment satisfies0.7<T(θ−φ)/T(θ)≦1, thereby making the transmittance of the light Lc andthe transmittance of the light La equivalent. T(θ−φ) and T(θ) arepotions having lower transmittance than other portions (portions with alarger angle), that is, a range in which the light is scattered. As aresult, it is possible to scatter the light Lc output at the angle |θ|−φcloser to the external light La side as illustrated in FIG. 9A. In otherwords, it is possible to scatter and attenuate diffracted light(diffraction light). This can suppress occurrence of iridescence at theangle |θ|−φ. Because the light can be scattered on the regularreflection light side with respect to the angle |θ|−φ, occurrence ofiridescence can be suppressed also on the regular reflection light side.The light Lb is regular reflection light having relatively highintensity compared with other angles. The regular reflection light canalso be scattered appropriately.

By contrast, the anisotropic scattering member according to thecomparative example does not satisfy 0.7<T(θ−φ)/T(θ)≦1, thereby makingthe transmittance of the light Lc higher than the transmittance of thelight La. Because the light Lc output at the angle |θ|−φ closer to theexternal light La side has high transmittance, the light Lc increasesthe ratio of passing through the anisotropic scattering member withoutany change as illustrated in FIG. 9B. In other words, diffracted light(diffraction light) is not much attenuated. This makes iridescence morelikely to occur at the angle |θ|−φ.

Although the explanation has been made of the case where θ is set to 20°and φ is set to 25° (2φ=50°) as illustrated in FIG. 10A in theembodiment, the values of the main incident angle θ and the scatteringangular range 2φ are not limited thereto. FIG. 10B illustrates the casewhere θ is set to 30° and φ is set to 25° (2φ=50°), for example. Also inthis case, when the anisotropic scattering member 20 satisfies0.7<T(θ−φ)/T(θ)≦1, occurrence of iridescence at the angle |θ|−φ can besuppressed. By contrast, FIG. 11 illustrates the case where θ is set to20° and φ is set to 20° (2φ=40°). In this case, when the anisotropicscattering member 20 does not satisfy 0.7<T(θ−φ)/T(θ)≦1, iridescence maypossibly occur at a position of the angle |θ|−φ.

As described above, when satisfying 0.7<T(θ−φ)/T(θ)≦1, the anisotropicscattering member can suppress occurrence of iridescence at a positionrotated on the incident light side with respect to the regularreflection light having relatively high intensity by a predeterminedangle, that is, at a position away from the regular reflection light bythe angle φ. This can reduce the risk that the image observer observesiridescence, thereby displaying a more preferable image to the imageobserver. Suppression of occurrence of iridescence at the angle θ−φ cansuppress occurrence of iridescence on the perpendicular line side of thedisplay surface in which iridescence is made more conspicuous.

In the anisotropic scattering member 20, the relation between thetransmittance T(θ−φ) and the transmittance T(θ) needs to satisfy0.7<T(θ−φ)/T(θ)≦1. By making the transmittance T(θ−φ) and thetransmittance T(θ) closer to each other, that is, by making thetransmittance at a position of regular reflection and the transmittanceat a predetermined position on the perpendicular line side of thedisplay surface closer to each other, occurrence of iridescence can besuppressed more appropriately.

By adjusting the widths of layers having different refractive indexes inthe anisotropic scattering member 20, that is, by adjusting the pitch,it is possible to adjust the scattering angular range 2φ. Specifically,making the pitch smaller can enlarge φ. By adjusting the inclinationangle of the boundary between the high refractive index area and the lowrefractive index area with respect to the Z-axis (axis extending in adirection perpendicular to the surface of the anisotropic scatteringmember 20) in the anisotropic scattering member 20, it is possible toadjust the scattering angular range 2φ.

The main incident angle θ is preferably set to −40° to −20° inclusive inthe anisotropic scattering member 20. Setting the main incident angle to−40° to −20° inclusive can make the angle of the regular reflectionlight Lb having high intensity 20° to 40° inclusive. This makes itpossible to output regular reflection light in a range of 20° to 40°inclusive serving as a range in which the image observer normallyobserves an image. Setting the main incident angle to −40° to −20°inclusive can prevent the visual line direction of the image observerfrom significantly deviating from the normal line of the image displayunit 1 when a light source is present just above the image display unit1, for example. This makes it possible to output brighter light in therange in which the image observer normally observes an image.

The relation between the main incident angle θ and the scatteringangular range 2φ preferably satisfies |θ|−φ<0 in the anisotropicscattering member 20. When |θ|−φ<0 is satisfied, occurrence ofiridescence can be suppressed at a position inclined to the direction inwhich the external light La enters with respect to the directionperpendicular to the surface of the anisotropic scattering member 20.

The scattering angular range 2φ is preferably set equal to or largerthan 50° in the anisotropic scattering member 20. More preferably, thescattering angular range 2φ is set to 50° to 90° inclusive in theanisotropic scattering member 20. This makes it possible to scatterlight at the angle θ and the angle θ−φ appropriately.

Second Embodiment

A second embodiment also relates to a display device according to thepresent disclosure.

The second embodiment is different from the first embodiment in that ananisotropic scattering member is arranged so as to scatter externallight incident from the outside while the light is passing through theanisotropic scattering member.

A display device 200 according to the second embodiment has the sameconfiguration as that of the first embodiment except for the arrangementof the anisotropic scattering member. Because the image display unit 1in FIG. 1 can be considered as an image display unit 2 and the displaydevice 100 can be considered as the display device 200, a schematicperpendicular view of the display device 200 according to the secondembodiment is not given. Because the image display unit 1 can beconsidered as the image display unit 2 by changing the arrangement ofthe anisotropic scattering member 20 in FIG. 2A as appropriate, aschematic perpendicular view for explaining the configuration of theimage display unit 2 according to the second embodiment is not given.

Also in the second embodiment, an anisotropic scattering member 20 isarranged as follows: external light enters from the surface in which achange in the refractive index occurring near the boundary between a lowrefractive index area 21 and a high refractive index area 22 isrelatively large; and the light exits as scattered light from thesurface in which a change in the refractive index occurring near theboundary between the low refractive index area 21 and the highrefractive index area 22 is relatively small. In the second embodiment,the anisotropic scattering member 20 is arranged so as to scatterexternal light incident from the outside while the light is passingthrough the anisotropic scattering member 20.

Similarly to the description of the first embodiment, the followingdescribes behavior of light in the image display unit 2 in the statewhere the incident direction of the external light and the normaldirection of the image display unit 2 form an angle β with reference toFIG. 12A.

As illustrated in FIG. 12A, the external light incident from the outsidepasses through a polarizing plate 33, a half-wave plate 32, and aquarter-wave plate 31, and enters the anisotropic scattering member 20.Unlike the first embodiment, the anisotropic scattering member 20 isarranged such that the direction in which the boundary between the lowrefractive index area 21 and the high refractive index area 22 extendsis substantially along the incident light. The external light enters anA-surface and exits as scattered light from a B-surface. The light exitsas scattered light from the surface in which a change in the refractiveindex occurring near the boundary between the low refractive index area21 and the high refractive index area 22 is relatively small. Thisreduces iridescent coloring due to light interference caused by themicrostructure. The light thus scattered passes through a liquid crystalmaterial layer 17, is reflected by reflecting electrode 16, and passesthrough the liquid crystal material layer 17 again. The light is thenincident on the B-surface of the anisotropic scattering member 20 andexits from the A-surface. Because the light enters in a directionsubstantially perpendicular to the direction in which the boundarybetween the low refractive index area 21 and the high refractive indexarea 22 extends, the light passes through the anisotropic scatteringmember 20 without any change. The light passes through the quarter-waveplate 31 and the half-wave plate 32 and reaches the polarizing plate 33.The light then exits to the outside.

By contrast, the following describes behavior of light in the case wherethe A-surface and the B-surface are switched in the anisotropicscattering member 20. The following describes behavior of light in animage display unit 2′ according to a comparative embodiment in which theA-surface and the B-surface are switched in the anisotropic scatteringmember 20 with reference FIG. 12B.

In this case, the light incident from the outside exits as scatteredlight from the surface in which a change in the refractive indexoccurring near the boundary between the low refractive index area 21 andthe high refractive index area 22 is relatively large. This rendersiridescent coloring due to light interference caused by themicrostructure conspicuous. The behavior from when the light thusscattered is reflected by the reflecting electrode 16 and to when thelight travels toward the outside is the same as the behavior describedabove.

In the second embodiment, the anisotropic scattering member 20 isarranged so as to scatter the external light incident from the outsidewhile the light is passing through the anisotropic scattering member.The light exits as scattered light from the surface in which a change inthe refractive index occurring near the boundary between the lowrefractive index area 21 and the high refractive index area 22 isrelatively small. This reduces iridescent coloring due to lightinterference caused by the microstructure.

The anisotropic scattering member 20 according to the second embodimentcan reduce the risk that the image observer observes iridescence whensatisfying 0.7<T(θ−φ)/T(θ)≦1. This makes it possible to display a morepreferable image to the image observer. Suppression of occurrence ofiridescence at the angle θ−φ can suppress occurrence of iridescence onthe perpendicular line side of the display surface in which iridescenceis made more conspicuous.

Third Embodiment

A third embodiment also relates to a display device according to thepresent disclosure.

The third embodiment is different from the first embodiment in that ananisotropic scattering member is formed by laminating a plurality ofscattering members having different scattering characteristics.

A display device 300 according to the third embodiment has the sameconfiguration as that of the first embodiment except for the structureof the anisotropic scattering member. Because the image display unit 1in FIG. 1 can be considered as an image display unit 3 and the displaydevice 100 can be considered as the display device 300, a schematicperpendicular view of the display device 300 according to the thirdembodiment is not given. Because the image display unit 1 can beconsidered as the image display unit 3 by changing the anisotropicscattering member 20 in FIG. 2A as appropriate, a schematicperpendicular view for explaining the configuration of the image displayunit 3 according to the third embodiment is not given.

FIG. 13 is a schematic exploded perspective view of the reflective imagedisplay unit according to the third embodiment.

As illustrated in FIG. 13, the image display unit 3 is formed bylaminating a scattering member 20A and a scattering member 20B. Thestructure and the arrangement of the scattering member 20A are the sameas those of the anisotropic scattering member 20 described in the firstembodiment.

The structure of the scattering member 20B is the same as that of theanisotropic scattering member 20 described in the first embodiment. Theimage display unit 3 is arranged such that the direction in which thelouver structure is inclined in the scattering member 20B is orthogonalto the direction in which the louver structure is inclined in thescattering member 20A.

The scattering member 20A and the scattering member 20B are different inthe direction of the scattering central axis and in the shape of thearea in which light is scattered. An anisotropic scattering member 320is formed by laminating a plurality of scattering members havingdifferent scattering characteristics.

Laminating a plurality of scattering members having different scatteringcharacteristics can adjust the scattering range of light.

If an area in which light is scattered in the scattering member 20A hasan elliptical shape with its longitudinal axis extending along theY-axis, for example, an area in which light is scattered in thescattering member 20B has an elliptical shape with its longitudinal axisextending along the X-axis. By laminating the scattering members 20A and20B, an area in which light is scattered has a substantially square andround shape. If the visual line moves up and down, or left and right tosome extent, the image observer can observe an excellent image.

With the laminated scattering members satisfying 0.7<T(θ−φ)/T(θ)≦1, theanisotropic scattering member 20 according to the third embodiment canreduce the risk that the image observer observes iridescence. This makesit possible to display a more preferable image to the image observer.Suppression of occurrence of iridescence at the angle θ−φ can suppressoccurrence of iridescence on the perpendicular line side of the displaysurface in which iridescence is made more conspicuous.

Fourth Embodiment

A fourth embodiment also relates to a display device according to thepresent disclosure.

The fourth embodiment is different from the first embodiment in that ananisotropic scattering member is formed by laminating a plurality ofscattering members having different scattering characteristics.

A display device 400 according to the fourth embodiment has the sameconfiguration as that of the first embodiment except for the structureof the anisotropic scattering member. Because the image display unit 1in FIG. 1 can be considered as an image display unit 4 and the displaydevice 100 can be considered as the display device 400, a schematicperpendicular view of the display device 400 according to the fourthembodiment is not given. Because the image display unit 1 can beconsidered as the image display unit 4 by changing the anisotropicscattering member 20 in FIG. 2A as appropriate, a schematicperpendicular view for explaining the configuration of the image displayunit 4 according to the fourth embodiment is not given.

FIG. 14 is a schematic exploded perspective view illustrating thereflective image display unit according to the fourth embodiment.

As illustrated in FIG. 14, the image display unit 4 is formed bylaminating a scattering member 20A and a scattering member 20C. Thestructure and the arrangement of the scattering member 20A are the sameas those of the anisotropic scattering member 20 described in the firstembodiment.

The structure of the scattering member 20C is the same as that of theanisotropic scattering member 20 described in the first embodimentexcept for the value of the angle α illustrated in FIG. 2B. The imagedisplay unit 4 is arranged such that the direction in which the louverstructure is inclined in the scattering member 20C is along thedirection in which the louver structure is inclined in the scatteringmember 20A.

FIG. 15 is a schematic sectional view illustrating the reflective imagedisplay unit according to the fourth embodiment.

The scattering member 20A and the scattering member 20C are different inthe direction of the scattering central axis and in the shape of thearea in which light is scattered. An anisotropic scattering member 420is formed by laminating a plurality of scattering members havingdifferent scattering characteristics. Laminating a plurality ofscattering members having different scattering characteristics canadjust the scattering range of light.

With the laminated scattering members satisfying 0.7<T(θ−φ)/T(θ)≦1, theanisotropic scattering member 20 according to the fourth embodiment canreduce the risk that the image observer observes iridescence. This makesit possible to display a more preferable image to the image observer.Suppression of occurrence of iridescence at the angle θ−φ can suppressoccurrence of iridescence on the perpendicular line side of the displaysurface in which iridescence is made more conspicuous.

In a display device according to the present disclosure, the anisotropicscattering member is disposed so that a light enters from a firstsurface thereof and exits as scattered light from a second surfacethereof, when an extent of refractive index difference at a boundary orvicinity thereof between the low refractive index area and the highrefractive index area is relatively large in the first surface andrelatively small in the second surface. Furthermore, the display devicesatisfies mathematical formulae,

0.7<T(θ−φ)/T(θ)≦1

θ<0

wherein 2φ represents a scattering angle range, θ represents apredetermined main incident angle of light entering the scatteringmember, T(a) represents a transmittance at a position on an extensionline of an incident direction of the light with an incident angle “a”.Owing to such features, it is possible to reduce the iridescence problemsuch as rainbow-colored glare, which may occur due to opticalinterference caused by a microstructure.

Although the invention has been described with respect to specificembodiments for a complete and clear disclosure, the appended claims arenot to be thus limited but are to be construed as embodying allmodifications and alternative constructions that may occur to oneskilled in the art that fairly fall within the basic teaching herein setforth.

For example, although the anisotropic scattering member is disposedbetween the front substrate 18 and the quarter-wave plate 31 inaforementioned respective embodiments, this is not exclusive. Thearrangement position of the anisotropic scattering member may bedetermined as appropriate depending on the design and the specificationsof the display device.

The technology of the present disclosure may employ the followingconfigurations.

-   (1). A display device comprising

a reflective image display unit including a sheet-like anisotropicscattering member, wherein

the sheet-like anisotropic scattering member has a surface in which botha low refractive index area and a high refractive index area exist,

the sheet-like anisotropic scattering member is disposed so that a lightenters from a first surface of the sheet-like anisotropic scatteringmember and the light entered from the first surface of the sheet-likeanisotropic scattering member exits as scattered light from a secondsurface of the sheet-like anisotropic scattering member,

the first surface has a relatively large difference of refractive indexbetween the low refractive index area and the high refractive indexarea,

the second surface has a relatively small difference of refractive indexbetween the low refractive index area and the high refractive indexarea, and

the display device satisfies mathematical formulae,

0.7<T(θ−φ)/T(θ)≦1

θ<0

wherein 2φ represents a scattering angle range, θ represents apredetermined main incident angle of light entering the scatteringmember, T(a) represents a transmittance at a position on an extensionline of an incident direction of the light with an incident angle “a”.

-   (2). The display device according to (1), wherein

the main incident angle θ is not less than −40 degrees and not more than−20 degrees.

-   (3). The display device according to (2), wherein

the sheet-like anisotropic scattering member satisfies a relationshiprepresented by a mathematical formula,

|θ|−φ<0

wherein θ represents the main incident angle and 2φ represents thescattering angle range.

-   (4). The display device according to (1), wherein

the scattering angle range 2φ is not less than 50 degrees and not morethan 90 degrees.

-   (5). The display device according to (1), wherein

the sheet-like anisotropic scattering member is disposed so that thescattered light is emitted when a light reflected in the image displayunit passes through the sheet-like anisotropic scattering member.

-   (6). The display device according to (1), wherein

the sheet-like anisotropic scattering member is disposed so that thescattered light is emitted when an incident light from outside passesthrough the sheet-like anisotropic scattering member.

-   (7). The display device according to (1), wherein

the image display unit comprises a reflective liquid crystal displaypanel including a front substrate, a back substrate, and a liquidcrystal material layer therebetween, and

the sheet-like anisotropic scattering member is disposed at a frontsubstrate side of the reflective liquid crystal display panel.

-   (8). The display device according to (1), wherein

the sheet-like anisotropic scattering member includes a plurality ofscattering members having different scattering characteristics, theplurality of scattering members being stacked or laminated.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. An anisotropic scattering memberformed into a sheet-like shape, comprising: a light incident surface;and a light emitting surface, wherein each of the light incident surfaceand the light emitting surface includes a low refractive index area anda high refractive index area, wherein each of the low refractive indexarea and the high refractive index area extends in a thickness directionfrom the light incident surface to the light emitting surface, whereinthe anisotropic scattering member satisfies T(α)<10%, and −10degrees≦α≦30 degrees, wherein α represents an angle between a normaldirection of the light incident surface and an incident direction oflight entering the light incident surface, and T(α) represents atransmittance at a position on an extension line of the incidentdirection with an incident angle (α).
 2. The anisotropic scatteringmember according claim 1, wherein T(α) is less than 8% when a range of αis −10 degrees≦α≦10 degrees.
 3. The anisotropic scattering memberaccording claim 1, wherein T(α) is more than 40% when a range of α isα<−20 degrees.
 4. The anisotropic scattering member according claim 1,wherein T(α) is more than 10% when a range of α is 40 degrees<α.
 5. Theanisotropic scattering member according claim 1, wherein T(α) is morethan 60% when a range of α is α<−30 degrees.
 6. The anisotropicscattering member according claim 1, wherein T(α) is more than 60% whena range of α is 50 degrees<α.
 7. A display device comprising: ananisotropic scattering member according to claim 1; and an image displayunit including a reflecting electrode that reflects an external light,wherein the anisotropic scattering member is provided on the imagedisplay unit in a state that the reflecting electrode is opposed to thelight incident surface of the anisotropic scattering member.